1. Field of the Invention
This invention relates to a continuous mining machine and more particularly a mining machine having a cutter drum drive assembly that includes input drive shafts canted at a preselected angle with respect to the longitudinal axis of the mining machine for positioning the cutter drum at a location forward of the gathering platform to facilitate efficient feeding of dislodged material on to the gathering platform.
2. Description of the Prior Art
Continuous mining machines, as illustrated in U.S. Pat. No. 3,774,969, are utilized in underground mining operations to continuously dislodge solid material from the face of a mine shaft. A boom member extends forwardly from an elongated body portion of the mining machine that is propelled through the mine on endless crawler tracks. The boom member is pivotally connected to the mining machine body portion and rotatably supports a cutter drum assembly having peripherally extending elements. The cutter drum assembly extends transversely to the longitudinal axis of the body portion and upon rotation, the cutting elements dislodge solid material from the mine face.
The cutter drum assembly is pivoted through an arcuate vertical path and sumped into the mine face to make a shear cut in the mine face. The dislodged material is fed rearwardly onto a gathering platform having suitable gathering devices which direct the dislodged material rearwardly onto a conveyor that extends longitudinally on the mining machine to transport the material toward the rear of the mining machine. By dislodging mineral material from the mine face in this manner a mine passageway or room is formed to thus permit the mining machine to advance and continuously dislodge material from the mine face.
Full face drum-type mining machines of the type illustrated in U.S. Pat. No. 3,305,273 are known to include support means and drive means for the drum. The support and drive means include fixed annular end portions of the boom member extending around the external surface of the drum. Endless chain elements with cutter bits mounted thereon extend around the support means to dislodge material from the mine face along the width of the annular end portions of the supporting boom.
In U.S. Pat. No. 3,774,969, as discussed above, the drum member has an intermediate drum section and canted end drum sections with rear openings between the inner ends of the end drum sections and the outer ends of the intermediate drum section. Input shafts extend through these openings and have drive pinions meshing with bevel gears rotatably supported within the intermediate drum section. The bevel gears are splined to shafts with sun gears of planetary gear trains nonrotatably mounted thereon. Planet gears of each planetary gear train are secured to the intermediate drum section and are rotated by the driven sun gear. The planet gears are also connected through universal joints to the adjacent canted end drum sections.
The above described arrangement of transferring rotation from the intermediate drum section through a planetary gear train to the respective end drum section requires a relatively large diameter intermediate drum section in order to accommodate the planetary gearing. However, a large diameter intermediate drum section has certain disadvantages in mining operations where the seam to be mined is relatively thin. Thus in this context the diameter of the cutter drum assembly and particularly the diameter of the intermediate drum section and the size of the drive gearing are limited by the mineral seam thickness. For this reason a drum drive arrangement with a planetary gear train in the intermediate drum section is not desirable for thin seam mining operations.
As further illustrated in U.S. Pat. No. 3,774,969, as well as in U.S. Pat. No. 3,848,930, a planetary gear train in the intermediate drum section transmits rotation to the canted end drum sections. The canted end drum sections extend outwardly at an angle with respect to the intermediate drum section so that the end drum drive shafts are not axially aligned with the intermediate drum drive shafts. The input drive shafts extend from the drive motors in parallel relation to the longitudinal axis of the mining machine. Because the end drum sections are canted outwardly, consequently the end drum drive shafts are positioned at an angle greater than 90.degree. with respect to the input drive shafts.
As above discussed it is preferably to position a planetary gear train in each end drum section rather than in the intermediate drum section. With this arrangement rotation is transmitted from the end drum sections to the intermediate drum section rather than from the intermediate section to the end drum sections. By positioning the planetary gear train in the respective end drum sections the base diameter of the intermediate drum section can be reduced to provide a more efficient dislodging operation, particularly in thin mineral seams. One advantage is the increased clearance provided around the intermediate drum section for the flow of dislodged material from the mine face onto the gathering platform. A smaller base diameter for the intermediate drum section would substantially prevent clogging of dislodged material between the mine face and the intermediate drum section because of the increased clearance made available between the mine face and the intermediate drum section.
For a mining machine having canted end drums, however, the end drum drive shafts are positioned at an angle greater than 90.degree. with respect to the input drive shafts. This arrangement provides insufficient area within the end drum sections for positioning a planetary gear train. There is need for a continuous mining machine having a cutter drum drive assembly which includes a planetary gear train in the end drum sections to permit a reduction in the base diameter of the intermediate drum section and thereby improve the overall efficiency of the cutter drum assembly to dislodge material from a mine face.
While it has been suggested to provide a cutter drum drive for transmitting rotation from the end drum sections to the intermediate drum section in which the drum sections are longitudinally aligned the prior art devices do not provide such a drive for a cutter drum having canted end drum sections. The prior art devices position the drive gearing in the intermediate drum section requiring the base diameter thereof to be enlarged. Thus a drive arrangement featuring planetary gear trains in the canted end drum sections would permit the use of an intermediate drum section of reduced diameter for thin seam mining operations.